Follow OpenBSD shared library naming scheme

Index: configure
--- configure.orig
+++ configure
@@ -2573,7 +2573,6 @@ SO_RELEASE=`echo $PACKAGE_VERSION | cut -f1,2 -d.`
 
 
 #LIBTOOL_VERSION_RELEASE="-version-info 0:0:0 -release @SO_RELEASE@"
-LIBTOOL_VERSION_RELEASE="-release $SO_RELEASE"